Eagles right guard Brandon Brooks arrived at Lincoln Financial Field for Sunday’s game with the Seattle Seahawks already feeling fatigued. Right away, he knew what it was.

His anxiety had resurfaced.

Usually Brooks is able to get the anxiety under control on game days. It hadn’t affected him to the point where he could not play since 2016 when he had to miss two games because it wouldn’t pass. That was his first season in Philadelphia, after the Eagles had signed him to a free agent contract after spending the first four years of his career with the Houston Texans.

Brooks tried to play on Sunday, but removed himself early in the first quarter. He did not return.

He was seen vomiting into a towel on the sideline before heading into the locker room.

“This is the first time I’ve had any experience with this type of thing,” said head coach Doug Pederson on Monday.

“I’ve seen guys back in my (playing) days in Green Bay work themselves up for games, go hit a trash can and they’re out playing. In Brandon’s case, this is real life for him. This is serious and it’s something he battles with every single day and does a great job managing that.”

Brooks has been outspoken about the anxiety issues he has had since first being diagnosed in 2016, wanting to bring awareness to the issue in order to help others who may be struggling with it.

Until Sunday, he had done a good job managing the issue.

Brooks is one of the Eagles’ best offensive linemen, and, earlier this month, the team rewarded him with four-year contract extension worth $54.2 million and will keep him in Philly through the 2024 season.

His early departure left an already-thinned-by-injury line in even further disarray.

The Eagles were already without Pro Bowl right tackle Lane Johnson, who was out with a concussion. In Johnson’s place was rookie Andre Dillard, who was playing right tackle for the first time in his life.

Halapoulivaati Vaitai stepped in at right guard for Brooks, but the Eagles benched Dillard to start the second half, which forced Vaitai to play right tackle and seldom-used Matt Pryor to enter at Brooks’ spot.

Pederson said he believes Johnson will be out of concussion protocol and be ready to practice on Wednesday.

Brooks’ condition won’t be known until game day this Sunday, when the Eagles travel to Miami to play the Dolphins at 1 p.m.